I've tried one of my boards after giving it a good scrub with isopropyl alcohol and as noted previously it sounds really dull and boring, nowhere near as bright as it should.
Mods so far...
Removed: C3, C24, C13, C21, R3, R16.
Added better input caps (3.3uF OSCON I think?), to replace C13, C21.
Added a 10,000uF tank cap across the power supply.
Powered by a dinky IBM Thinkpad SMPS 16V 4.5A
After the modifications it sounds pretty good into my Richard Allan 8ohm monitors, and with 16V it seems to have a bit more go with it. I guess that the tank cap will have helped also.
There is definately bass there, but I think it still lacks definition when compared to the more beefy TA2022 based AMP10-BASIC. I don't have a SI T-AMP to compare against unfortunately, but I suspect the same. Who knows, maybe those little SMT caps will run in.
Mods so far...
Removed: C3, C24, C13, C21, R3, R16.
Added better input caps (3.3uF OSCON I think?), to replace C13, C21.
Added a 10,000uF tank cap across the power supply.
Powered by a dinky IBM Thinkpad SMPS 16V 4.5A
After the modifications it sounds pretty good into my Richard Allan 8ohm monitors, and with 16V it seems to have a bit more go with it. I guess that the tank cap will have helped also.
There is definately bass there, but I think it still lacks definition when compared to the more beefy TA2022 based AMP10-BASIC. I don't have a SI T-AMP to compare against unfortunately, but I suspect the same. Who knows, maybe those little SMT caps will run in.
A couple of pictures.
..tie wrapping the tank cap through the speaker post holes seems to work a treat
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
..tie wrapping the tank cap through the speaker post holes seems to work a treat
After a good run in and trying it with a few different audio inputs last night, I can confirm that this is actually a pretty good little amp. It's definately got the precision and "*twinkle*" that my other 41hz.com AMP10-B has, but obviously lacks the grunt. It's definately good value!
Now time to add a volume pot and find a nice little box to put it in, has anyone come across any UK suppliers of nice small aluminium enclosures? (excluding the usual Farnell, Maplin etc)
Now time to add a volume pot and find a nice little box to put it in, has anyone come across any UK suppliers of nice small aluminium enclosures? (excluding the usual Farnell, Maplin etc)
I wouldn't take mine over 13.8V at the chip as per Tripath recommendation.
...well mine ran fine for about 3 hours without damage, I don't want to be responsible for any explosions! 
I might put a heatsink on the chip, my guess is that the core temperature could be approaching 150 degrees at 16V VDD when played loud.
Audio1st: Are you able to post the full schematic that you worked out for the board?
I might put a heatsink on the chip, my guess is that the core temperature could be approaching 150 degrees at 16V VDD when played loud.
Audio1st: Are you able to post the full schematic that you worked out for the board?
Bongoman: Thanks for sharing the detailed pics and the mod summary.
I am waiting for my board to arrive and will be following your lead
Rgds
Mayank
PS I don't know if anyone has noticed this, but there is another "newer" seller who has listed a few of these boards on eBay. His ID is sureelectronics1 and seems to be from a different city in China but has identical description and pictures. I chose to stay with the "original" sureelectronics.
I am waiting for my board to arrive and will be following your lead
Rgds
Mayank
PS I don't know if anyone has noticed this, but there is another "newer" seller who has listed a few of these boards on eBay. His ID is sureelectronics1 and seems to be from a different city in China but has identical description and pictures. I chose to stay with the "original" sureelectronics.
I forgot to mention before, I turned the power terminal block around 90 degrees to make the wiring a bit neater for the tank cap.
I think I'll replace that large 10,000uF electrolytic with a much smaller one or a number of smaller caps, otherwise I'll need a chunky enclosure. I'm sure that much capacitance is overkill anyway.
I think I'll replace that large 10,000uF electrolytic with a much smaller one or a number of smaller caps, otherwise I'll need a chunky enclosure. I'm sure that much capacitance is overkill anyway.
Update of Mods so far:
C21 & C13 replaced with 2.2uf Epcos MKT.
C3 & C24 removed.
R3 & R16 replaced with 1M ohms.
R1 & R18 replaced with 15k in series with 10k trimmers for DC offset adjustment.
R8 & R14 replaced with 26k7 0.1% 15PPM resistors.
R7 & R13 replaced with 31k6 0.1% 15PPM resistors.
D1 removed and bridged.
2 Panasonic FM 330uf 35V added near chip.
2 Panasonic FC 2200uf 16V added on rails.
That's it for now, received a couple of V1.2 boards today so I can compare in the future.
PS I must clean that board!
C21 & C13 replaced with 2.2uf Epcos MKT.
C3 & C24 removed.
R3 & R16 replaced with 1M ohms.
R1 & R18 replaced with 15k in series with 10k trimmers for DC offset adjustment.
R8 & R14 replaced with 26k7 0.1% 15PPM resistors.
R7 & R13 replaced with 31k6 0.1% 15PPM resistors.
D1 removed and bridged.
2 Panasonic FM 330uf 35V added near chip.
2 Panasonic FC 2200uf 16V added on rails.
That's it for now, received a couple of V1.2 boards today so I can compare in the future.
PS I must clean that board!
Attachments
Excellent work audio1st!
I think I'm going to put a couple of trimmers in too, I'm seeing a 47mV DC bias on the outputs that ideally should be far lower (better than 500mV as standard though!).
I'm also going to put in a few LEDs, a power indicator from 5VGEN, and another couple switched from OVERLOADB and FAULT with transistors.
Audio1st, please can you post the full schematic that you posted the input side of previously, it would help enormously!
I think I'm going to put a couple of trimmers in too, I'm seeing a 47mV DC bias on the outputs that ideally should be far lower (better than 500mV as standard though!).
I'm also going to put in a few LEDs, a power indicator from 5VGEN, and another couple switched from OVERLOADB and FAULT with transistors.
Audio1st, please can you post the full schematic that you posted the input side of previously, it would help enormously!
Audio1st: Many thanks for posting the other side of the Schematic, it's just nice to know what everything does on the board, since it's covered in black stuff.
Further Mods:
I can't really notice any difference with the sound, I'm sure that running at a lower DC bias is "healthier" though.
I think my next little project with this board will be to piggyback a CS8416 -> CS8421 (upsampling to 192khz/24) -> 2xTDA1543, to make a nice digital input integrated amplifier. If anyone has experience with getting a CS8421 working, I'd love to hear from you as it's got me beaten so far!
...Now onto the LEDs.
Further Mods:
- Added a couple of 50k 25TRN trimpots to replace the original static R1, R2 and R15, R16 input biasing voltage dividers. With some careful bending and soldering I managed to get the trimpots wired directly onto the SMT pads.
- Replaced R3,R16 back to standard.
- Replaced C9,C19 with 70uF 25v electrolytics.
- Replaced the chunky 10,000uF tank cap with a slimmer 4700uF 40v electrolytic.
- Trimmed the DC bias for both channels down to <2mV
I can't really notice any difference with the sound, I'm sure that running at a lower DC bias is "healthier" though.
I think my next little project with this board will be to piggyback a CS8416 -> CS8421 (upsampling to 192khz/24) -> 2xTDA1543, to make a nice digital input integrated amplifier. If anyone has experience with getting a CS8421 working, I'd love to hear from you as it's got me beaten so far!
...Now onto the LEDs.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I have power and overload LEDs now. It seems that the OVERLOAD pin on the chip is not connected to anything (unless anyone has found different?). Therefore the only option remaining for connecting to it is a direct connection to the TA2024, which isn't much fun at all!
PLEASE DON'T ATTEMPT THIS UNLESS YOU ARE COMFORTABLE WITH REALLY SMALL AND FIDDLY SOLDERING!!
I successfully managed to lift the OVERLOAD pin from the TA2024 with a needle and connect a wire to it. Since this pin is at 5v during normal operation and 0v with an overload condition I made a simple NOT gate using a NPN transistor and a couple of resistors to drive the RED LED. The GREEN LED is a permanent on indicator and just uses a 4.7k resistor to reduce the current (could probably do with a 1k for more brightness)
Now I just need to pluck up the courage to lift the FAULT pin and then I can stabilise the pin connections with some epoxy.
...This isn't the final setup by the way
PLEASE DON'T ATTEMPT THIS UNLESS YOU ARE COMFORTABLE WITH REALLY SMALL AND FIDDLY SOLDERING!!
I successfully managed to lift the OVERLOAD pin from the TA2024 with a needle and connect a wire to it. Since this pin is at 5v during normal operation and 0v with an overload condition I made a simple NOT gate using a NPN transistor and a couple of resistors to drive the RED LED. The GREEN LED is a permanent on indicator and just uses a 4.7k resistor to reduce the current (could probably do with a 1k for more brightness)
Now I just need to pluck up the courage to lift the FAULT pin and then I can stabilise the pin connections with some epoxy.
...This isn't the final setup by the way
An externally hosted image should be here but it was not working when we last tested it.
Nice work Bongoman..
You should try some better input and feedback resistors, seem to make a difference with top end sparkle.
I've teamed mine up with a 12V , 6A power supply, also from SURE , turned up to 13.5V (so far)...
I have removed the second stage of the output filter and put a single cap across the speaker terminals at the moment, (haven't listened yet)
I really like these boards...
You should try some better input and feedback resistors, seem to make a difference with top end sparkle.
I've teamed mine up with a 12V , 6A power supply, also from SURE , turned up to 13.5V (so far)...
I have removed the second stage of the output filter and put a single cap across the speaker terminals at the moment, (haven't listened yet)
I really like these boards...
Attachments
C8,C11,C17,C20 (The last caps in the output filter) all seem to be not needed if I'm reading the datasheet correctly. Let me know if removing them has brightened up the top end and I'll do the same. It just seems like an unnecessary low pass filter and could be attenuating the higher frequencies.
I'll replace the feedback resistors with some 22K metal films, it seems a sensible change.
Where did you source your cases from audio1st?
I'll replace the feedback resistors with some 22K metal films, it seems a sensible change.
Where did you source your cases from audio1st?
Cases are just the plain Hammond (Maplin), or if you need a longer case, as I did, then Rapid .
That's also where I got the 0805 surface mounts. The reason for the strange value of input and feedback resistors I used is they were cheap, none ROHS (my first time with new SMD's)..
No adverse effects yet from the missing output filter, I'll have a serious listen tonight, easy enough to replace with new caps if it doesn't workout.
PS the fist stage is more like 500nf than the 330nf shown on the diagram. (very hard to measure as they vary with temp)
That's also where I got the 0805 surface mounts. The reason for the strange value of input and feedback resistors I used is they were cheap, none ROHS (my first time with new SMD's)..
No adverse effects yet from the missing output filter, I'll have a serious listen tonight, easy enough to replace with new caps if it doesn't workout.
PS the fist stage is more like 500nf than the 330nf shown on the diagram. (very hard to measure as they vary with temp)
I bought a bag full of SMD resistors and capacitors from Sure, but they Sure haven't arrived yet!
SMD Caps and Res
At the moment I'm mostly using conponents scavenged from my first AMP10-B kit and various other broken things, but I needed some SMD components to build my DAC project.
I think for this project I'll get a small Hammond case, they look better than I thought they would actually. For the AMP10-B I think I'm going to fabricate a box from aluminium sheet as it has a rather large 500VA transformer that needs a bit more room.
SMD Caps and Res
At the moment I'm mostly using conponents scavenged from my first AMP10-B kit and various other broken things, but I needed some SMD components to build my DAC project.
I think for this project I'll get a small Hammond case, they look better than I thought they would actually. For the AMP10-B I think I'm going to fabricate a box from aluminium sheet as it has a rather large 500VA transformer that needs a bit more room.
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